The Gavin and Stacey star made Christmas movie Nativity 2 in locations across Coventry and Warwickshire last year, wearing a fake bump as a mum-to-be.

But now, just as the film is released, she is experiencing the REAL thing – she’s almost seven months pregnant.

Joanna just hopes her labour won’t be in a stable surrounded by eight-year-olds and a donkey.

“We filmed from 8am to 11pm and by the end I was exhausted. I felt like I had really given birth!” laughs the 35-year-old, who is married to former Emmerdale actor James Thornton.

“I imagine my labour will be slightly more painful but it really felt like hard work.

“And for days afterwards, every time I undressed I found bits of hay stuck to my body.

“I absolutely loved having a fake pregnancy bump, as it kept me so warm. It felt comforting, like someone was hugging me all the time. I didn’t take it off even during lunch.

“Now I wish my real bump wasn’t so heavy and I could take it off at night when I can’t sleep!

“The donkey, called Archie, that we filmed with was so cute. But every time I sat on him, he would either bolt or refuse to move, so I’d just hang on to David Tennant for all I was worth.”

Nativity 2: Danger in the Manger is released on Friday and is the sequel to Birmingham-born Debbie Isitt’s hit 2009 film.

Debbie Isitt

Once again, it is set in the fictional Coventry primary school of St Bernadette’s, although this time the teacher is not Martin Freeman but David Tennant as Donald Peterson. Joanna plays his wife, Sarah.

Debbie’s unique way of filming is that the script is all improvised by the cast.

“I was terrified at first,” confesses Joanna. “I felt so under-prepared because I’d had no lines to learn, but I soon got used to it.

“It was great working with David as he’s so good at improvising and made me laugh all the time.”

The finalé of the film, in which the pupils take part in a national singing contest, was filmed at the Royal Shakespeare Company’s Courtyard Theatre in Stratford-upon-Avon.

“It really took me back because I visited the theatre a lot as a teenager,” says Joanna. “I saw Kenneth Branagh in Hamlet. I remember wandering around the town in my flares and velvet jacket, dreaming of being married to him – I idolised him!”

Joanna returned to the Midlands last week to open the new branch of Superdrug in the Merry Hill shopping centre at Brierley Hill.

She is the face of the pharmacy chain but proved that she is a real fan by becoming their first customer.

“As soon as I got there, I said ‘Before I cut the ribbon I need to do some shopping’.